Indiana Attorney General Todd Rokita has launched “Operation Robocall Roundup” to combat illegal robocalls.

The AG’s office, in partnership with a national task force, has sent warning letters to 37 voice service providers.

The letters demand they stop routing illegal robocalls through their networks, accusing them of failing to follow federal rules.

The task force is also working with the FCC, which is removing several providers from its robocall database as part of the effort.